Human families with inherited disorders will be typed for more than 35 genetic marker systems and in some cases by centromeric and fluorescent chromosome staining in a search for new genetic linkage relationships. BIBLIOGRAPHIC REFERENCES: Weitkamp, L. R., Schwartz, R. H., and Cox, D. 1976. Possible association between the Duarte gene of galactose-l-phosphate uridyl transferase and the ZZ or SZ genotype of alpha l-antitrypsin. Birth Defects Conference (Kansas City, 1975), in press. Edwards, J. H. and Weitkamp, L. R. 1976. Report of the committee on unassigned linkage groups. Third International Gene Mapping Conference, Baltimore, Md. (1975). Cytogen. and Cell Genet., in press.